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Description Based addressing and routing

in Cluster-based Ad-Hoc network

for Home Environment

By

Tharinda Nishantha Vidanagama

Supervised by,

Prof. Hidenori Nakazato

Honjo Seminar 2009 12 01

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Ad Hoc Networks

The Ad Hoc peer network is created spontaneously as two participating nodes come within the reach of one another.

As the number of participating nodes and their positions vary the network it self reconfigures allowing all nodes to communicate even if they are not within their transmission range.

The main advantage of Ad Hoc networks is that they do not require any infrastructure to operate.

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Ad Hoc Networks

But the main disadvantages are Highly dynamic topology due to the mobility of the nodes, i.e. the links

are not stable and bandwidth is limited. Mobile devices are powered by batteries, putting an energy

consumption constraint Security of the network is at risk as anyone can join the network and act

as transmission mediators.

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Ad Hoc Networks

Increasingly wireless technology is build in to many devices.

Networking these devices can bring many benefits.

Range of application is vast. Military Disaster Mobile phone service extension.

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Description based Ad Hoc Networks

Communication failures are considered normal in Ad-hoc networks.

Description based addressing instead of host based(IP) addressing is more appropriate because it will not rely on a single path, but uses multicasting .

In description-based routing, selective information dissemination can be implemented.

Easy to understand and manage the network.

This will minimize control data among peers and facilitate group communication.

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Ad Hoc Network at Home !

Increasingly new functions are built in to home appliances.

Home appliances fitted with wireless communication modules would become more common in near future.

The system for home networking would provide information required for inter-working environment for home appliances and it’s users.

The nodes in this environment could also have the following constraints, Low memory Low transmission distances Some nodes may have limited power supply.

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Ad Hoc Network at Home ?

What about the Ad Hoc network disadvantages?

Household appliances are mostly static i.e. they may not move at all. Therefore the problems arising due to mobility is very limited.

Almost all appliances are plugged in to an unlimited power supply, therefore the power limitations doesn’t apply.

The whole network is owned by one owner, there is no security risk within the network.

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Add Hoc home network - Approach

1. Cluster Based Ad Hoc Network

2. Description Based Routing and Addressing

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1. Cluster Based Add Hoc Network Why?

At home most appliances are clustered in places. Kitchen Living room Bed room etc.

Clustering also reduces the amount of control data exchanged among the nodes.

Only a portion of the nodes are involved in the actual routing process.

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Cluster Based Add Hoc Network Organization

Everyone knows its one hop neighbors (Neighbor Table).

Cluster heads know their neighboring cluster heads (Cluster Adjacency Table).

Member nodes send their messages to their respective cluster heads to be forwarded to their destinations.

Only cluster heads and gateways forward messages.

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Problem of Routing Does a cluster head know about all other cluster heads?

This requires high memory capacity !

How to route messages beyond known cluster range?

A fixed size Routing Cache (RC) is used to keep track of the nodes that are beyond range.

Rather than using a table structure this helps reduce the memory usage.

There is no need to store the full identities or routs.

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We assume that identifiers given to the nodes in the network i.e. home appliances are similar to the following examples.

Kitchen oven, Kitchen television, Living room television etc.

In this natural language usage, a general location is identified from the beginning words and becomes more specific within that particular area by the next words.

Our routing algorithm routes the data messages in the direction of the destination.

When the message finally arrives at the particular region, there would be nodes that store the exact identifier in their Neighbor table, thus allowing the message to be delivered to the correct destination node.

2. Description Based Routing and Addressing

 

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How the Routing Cache is used?If a cluster head or gateway node comes across another cluster head that is beyond its range, it inserts the name in to the RC.

E.g: if the required destination is “kitchen oven” but the RC entry may be “kitchen”.

This partial match is enough to ensure that the message gets routed in the direction of the kitchen.

If the entry is in the 1st position of the RC it would be as follows.

Routing Cache Usage

 

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15

nehctik

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Routing Cache Storage For the simulation purpose we use a fixed size character RC. Elements are inserted in a way that some of the information about

old entries are overwritten by new entries. If,

S - RC sizep - Number of parts the RC is divided in to ( p = 2x,

where x = 0, 1, 2… and Total possible RC entries = 2p)P - The next position in RC to be occupied q - (1) If entry number is an odd number

(+1) If entry number is an even number.

When an entry is made in to the RC the starting position (T) for an entry is given according to the following formula.

Starting Position T= ( / ) * ( )S p P q

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Routing Cache storage The number of characters allocated for an entry in the RC is given by the

following formula,

Number of characters =

The actual character positions are given by a modified version of the Fibonacci series (0, 1, 2, 3, 5…), where we have omitted the repetition of number 1. Character position in the RC is given by the following formula,

( / ) 1ps

; 1.; 1. = {T f q

T f qCharacter Position

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Tabular Support Structures

Neighbor Table (NT): Holds the information about a node’s one-hop neighbors that have a bi-directional link. It holds the neighbor’s

identifier and its status.

Cluster Adjacency Tables (CAT): Holds the information about the neighboring clusters. A neighboring CH can be two or three hops away. The CAT holds CH identifier and the GW identifier, which is the next immediate hop in the direction of that cluster head.

Routing Cache Table (RCT): This will be used to store directional RC. This table will store the one hop identifier (of a GW) of each available bi-directional link that has clusters beyond itself and RC for that direction. All the nodes keep an NT, but the CHs and the GWs also keep the CATs and may also use RCT.

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Types of Messages

1. Control Messages- Control messages are sent only to a node’s one-hop neighbors.

- All control messages are terminated at their one-hop neighbors.

- The receivers update their CAT, NT and RC/RCT with the new control data and create new control messages that are sent to its neighbors. This way the entire network is configured.

ID Name of the sender

Status Status of the sender

NT NT of the sender

CAT CAT of the sender (CH and GW nodes)

RC/RCT RC/RCT of the sender (CH and GW nodes)

RC/RCT Entries Number of Entries for each RC

Description Type of message

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Handling a Control Message

When a node receives a Control Message,If receiver is a CH and previous sender is a GW node or this node is a GW and previous sender is a CH,

- If the sender is unknown then Add as a neighbor

- All known CH of the sender that it has a direct link or it is through another GW node (this GW node must be a neighbor node of the

previous sender) are inserted to this CH’s CAT.

- All other CAT entries are inserted to RC/RCT.

- Previous sender’s NT entries that are not even partially known are inserted to the RC/RCT.

- Sender’s RC/RCT entries that are not even partially known are also inserted to the RC/RCT.

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Types of Messages

2. Data Messages

- Nodes arbitrarily generate data messages after the network has configured.

ID Name of the sender

MsgID Message identifier

Status Status of the sender

Description Type of message

Destination Message destination

Prev.Sender Previous sender

Nxt. Receiver Next receiving node (only for directional routing)

TTL Available number of hops

Data Data carried by the message

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Handling Data Messages

When a node receives a Data Message, If destination is this node

Consume dataElse if I am Gateway/Cluster head and if this data has not already been

forwardedLook for destination in neighbor table

If not found Look for destination in Cluster Adjacency table

If not foundLook for partial match in Cluster Adjacency table

If not found Look for partial/complete match in the RC/RCT.

If foundForward message

ElseDiscard message.

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A simulation program was developed in order to evaluate the above proposal.

We have used an environment, which is a flat surface 25*25 square units, where 100 nodes are statically located.

The size of the RC was limited to 128 characters. Each node has various transmission distance (maximum of 3 units)

and priorities. Each node will send a number of messages to randomly selected

destinations.

Evaluation

 

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Evaluation – Message broadcast

It shows 100% success rate on message delivery with the current environment setting.

But… message misdirection is very high !!!.

 

Average Message Misdirection Using Broadcast

0100200300400500600700800900

1000110012001300

500 1000 1500 2000 2500 3000 3500 4000 4500 5000

Data msgs

Per

cen

tag

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success Average Drop

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Evaluation – Single Routing Cache

It shows on average a 100% success rate on message delivery with the current environment setting.

But… message misdirection is still high !!!.

Average data message misdirection Single RC

020406080

100120140160180200220

500 1000 1500 2000 2500 3000 3500 4000 4500 5000

Data messgaes

Per

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Average misdirection Success

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The message misdirection occurred because of the use of single RC. RC entries do not store the direction of that particular entry. Therefore the

messages maybe forwarded to the wrong way as well.

Evaluation – Why the misdirection?

  GW

CH

CH

128

128

128

CH

128

128

CH

GW

Bidirectional link

Routing Cache

Cluster Head

Gateway

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Solution – Directional Routing Cache Routing nodes are given a RC

for each outward link. The nodes can now compute

the next hop of the messages in the right direction.

GWCH

128

128

128

CH

GW

Bidirectional link

Routing Cache

Cluster Head

Gateway

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The message misdirection is significantly reduced by the directional RCs.

But the Memory usage is High and unpredictable !!!

Simulation – Directional Routing Cache

Average data message misdirection Directional RC (Equal-sized)

0

20

40

60

80

100

120

500 1000 1500 2000 2500 3000 3500 4000 4500 5000

Data messgaes

Pe

rce

nta

ge

Average drop Success

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The RC is divided proportionally between each bidirectional link.

Initially full size given to first bidirectional link with a RC entry.

If another link has a RC entry the RC is proportionally divided among the links according to the number of entries in each direction.

Solution: Proportional Directional RCs

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Success at 100%

Simulation:Proportional Directional RCs

Average data message misdirection Proportional Directional RC

0

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100

120

500 1000 1500 2000 2500 3000 3500 4000 4500 5000

Data messgaes

Per

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The performance is similar to the equal-sized directional RCs

Equal-sized RC Vs Proportional directional RC

Average Data Message MisdirectionProportional Directional RC Vs Equal-sized RC

0

10

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500 1000 1500 2000 2500 3000 3500 4000 4500 5000

Data messages

Per

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age

Proportional directional RC Equal-sized directional RC

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When a message is received by a node that has many outward links, it checks each RC for a match with the destination.

If more than one RC is positively matched the node has to broadcast the message to all outward links.

Thereafter only the next hop nodes who know the destination will forward the message, and the others will register a lost message.

Directional RCs – remaining message drop

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The loss due to wrong routing is significantly reduced by the directional RCs.

Simulation ComparisonData Message loss Comparison

at 100% success rate

0100200300400500600700800900

1000110012001300

500 1000 1500 2000 2500 3000 3500 4000 4500 5000

Data messages

Per

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Broadcasting Single buffer Directional buffer

%

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Considering that a home environment does not contain large number of nodes, this algorithm can be effectively implemented.

The use of clustering has further supported in reducing the network traffic and routing overhead.

Use of descriptions improves the user understandability of the system. Use of directional RCs will significantly reduce the message loss and

improve resource usage. Proportional directional RC is the solution with most preferable

settings. The amount of misdirected messages is also independent of the

amount of data sent by any node.

Conclusion

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We will study the performance and issues when movement is introduced to the network nodes. In the home environment elements such as cell phones and laptops etc, will have movement associated with them.

We would also like to find the optimal RC size for a given number of nodes.

Further decrease the amount of control information held and transmitted by nodes.

Future extensions

 

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[1] Tim Daniel Hollerung, “The Cluster-Based Routing Protocol”- project group ‘Mobile Ad-Hoc Networks Based on Wireless LAN’- 2003/4P.

[2]Krishna, N.H. Vaidya, M. Chatterjee and D.K. Pradhan. “A cluster-based approach for routing in dynamic networks”. ACM SIGCOMM Computer Communication Review 27:49-65, 1997.

[3] M. Petorvic, V. Muthusamy, H.Jacobsen, “Content-Based Routing in Mobile Ad Hoc Networks”,IEEE MobiQuitous, 2005.

[4] Mario Gerla and jack Tzu-Chieh Tsai, “Multicluster, Mobile, Multimedia radio network”. ACM- Baltzer Journal of Wireless Networks ,1: 255-265, 1995.

[5] R.C.Shah and J.M. Rabaey, “ Energy aware routing for low energy ad hoc sensor networks”,0-7803-7376-6/02 IEEE 2002, pp.350-355.

[6] Tharinda N. Vidanagama, Hidenori Nakazato, “Description Based Routing and Addressing in Cluster Based Ad Hoc Network” IEICE General Conference, 2009.

[7] Tharinda N. Vidanagama, Hidenori Nakazato, “Reduction of Message Misdirection in Description Based Clustered Ad Hoc Networks”, (To be presented at 7th IEEE CCNC PerNets workshop).

Reference

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In a home environment nodes have a limited, Space, Available starting positions, Destinations.

Infrequently moving nodes are also considered as static.

Introducing Node Movements

 

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1. Observe node and classify them accordingly.

- all nodes start as static nodes.

- The nodes should monitor their own movements.

- One method is to check whether its cluster changes from time to time.

but what if the cluster moved and not the node?

Do clusters move in a home environment?

Movement Options

 

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2. Vary the “Hello” message or the beaconing frequency proportional to the node movement speed.

- In this case the node it self should measure its own speed and adjust the beaconing frequency accordingly.

- rate of changing of clusters can be used as a measure of movement speed.

Introducing Node Movements

 

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3. Use a random way point model.

- Randomly select nodes and move them to random destinations.

- In a home environment node can not have random routes.

- There are only a number of fixed routes a node can take?

- The routes depend on the architecture of the house !

Introducing Node Movements

 

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Thank you !

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Questions ?